class Lady {
  content: string = 'Hi'
  sayHello(): string {
    return this.content
  }
}

const goddess = new Lady()
console.log(goddess.sayHello())

class Xiaojiejie extends Lady {
  sayLove() {
    return 'I Love You'
  }
  sayHello() {
    return super.sayHello() + '你好'
  }
}

const person = new Xiaojiejie()
console.log(person.sayHello(), person.sayLove())
